There is an entire ecosystem in a previously-overlooked layer of a rainforest. Between the treetops and the forest floor, falling leaves are caught in a matrix of almost-inivisible filaments of the fungus Marasmius. Jake Snaddon from the University of Oxford has been studying this in-between layer of leaves and fungus.

When Snaddon shifted his focus to these hanging leaves, he soon realised their importance. In every hectare (the size of a rugby pitch, or London’s Trafalgar Square), the fungi hold around 260 kilograms of leaves. They hold 2-3 times more than other epiphytes can, and they’re more evenly dispersed.

These litter-traps are suspended worlds. Snaddon counted around 340 different species of insects and other arthropods among the dead leaves. If he removed the fungi, the number of species in the lower canopy fell by 57 percent, and the total number of individuals fell by 70 percent. That’s a huge figure, especially when you consider that around 60 percent of the canopy’s arthropods live in its lowest parts. Clearly, our knowledge of the rainforest was missing a crucial layer.

Next Snaddon will look at the relationships between the different species of life in the rainforest mezzanine. Link